Background & Objective : It has been suggested that wounds are a source of post-surgical host immunosuppression, and that this is partly attributable to cytokines and arachidonic acid metabolites produced by platelets and inflammatory cells. Wound and peritoneal fluids (WF & PF) contain several growth factors which mediate repair processes. Transforming growth factor-beta (TGF-beta), which is found in WF and PF following surgery, is known to have immunosuppressive activity. This study, was therefore designed to examine the effect of breast and gastric cancer surgery on systemic immune response, in terms of potential correlation with TGF-beta_1 and prostaglandin E_2 (PGE_2) in WF and PF after surgery.Methods : The levels of TGF-beta_1, PGE_2 and hepatocyte growth factor (HGF) in post-surgical WF and PF were assayd sequentially. Concomitant changes in NK cell activity (NK) and soluble IL-2 receptor (sIL-2R) were measured in the patients who underwent surgery. Assay of NK was performed in nude mice following intraperitoneal (IP) administraion of TGF-beta_1.Results : High levels of TGF-beta_1, and PGE_2 were observed in WF and PF on day 1 after surgery. Although the levels of TGF-beta_1, and PGE_2 in PF remained high on days 1 through 5, thir levels decreased in WF on day 3. A prolonged decrease in NK was observed after gastrctomy compared with mastectomy. Serum sIL2-R levels was increased after gastrctomy, whereas no differences was observed after mastectomy. Detectable levels of HGF in WF and PF were also observed. Supernatant of WF and PF suppressed NK in normal volunteeers, and PF was more suppressive than MF.Administation of TGF-beta_1, suppressed NK in nude mice.Conclusion : A decrease in systemic immune response was prolonged following gastrectomy as compared to mastectomy, and cytokines in WF and PF from patients who have undergone surgery may impair NK activity.